The bowels of hell used to disgorge metal messiahs like Avenged Sevenfold all the time. But these days, the band’s vision of mainstream headbanging is as adorably quaint as a glow-in-the-dark Iron Maiden poster in a rec room that Dad converted to storage space in 1994. Fusing elements of goth, screamo and what was once called nu metal with the late-Seventies new wave of British metal-metal, their sixth LP piles clarion solos atop clean, sludge-chug riffs. Vocalist M. Shadows nearly busts a kidney calling down a Satan-y apocalypse on “Shepherd of Fire,” and the ballad-storm “Acid Rain” is Romeo and Juliet by way of Queensrÿche. Suicide: still a solution after all these years.